/* * Copyright 1999-2001,2004 The Apache Software Foundation. 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at
 *     
 *   http://www.apache.org/licenses/LICENSE-2.0 
 *   
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License. 
 * */
package cn.bopomo.dealer.base.util;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

/** <p>Example filter that sets the character encoding to be used in parsing the 
 * incoming request, either unconditionally or only if the client did not 
 * specify a character encoding.  Configuration of this filter is based on 
 * the following initialization parameters:</p> 
 * <ul> 
 * <li><strong>encoding</strong> - The character encoding to be configured 
 *     for this request, either conditionally or unconditionally based on 
 *     the <code>ignore</code> initialization parameter.  This parameter 
 *     is required, so there is no default.</li> 
 * <li><strong>ignore</strong> - If set to "true", any character encoding 
 *     specified by the client is ignored, and the value returned by the 
 *     <code>selectEncoding()</code> method is set.  If set to "false, 
 *     <code>selectEncoding()</code> is called <strong>only</strong> if the 
 *     client has not already specified an encoding.  By default, this 
 *     parameter is set to "true".</li> 
 * </ul> 
 * 
 * <p>Although this filter can be used unchanged, it is also easy to 
 * subclass it and make the <code>selectEncoding()</code> method more 
 * intelligent about what encoding to choose, based on characteristics of 
 * the incoming request (such as the values of the <code>Accept-Language</code> 
 * and <code>User-Agent</code> headers, or a value stashed in the current 
 * user's session.</p> 
 * * @author Craig McClanahan 
 * @version $Revision: 1.3 $ $Date: 2004/02/28 03:35:22 $ 
 */

public class SetCharacterEncodingFilter implements Filter {    
	// ----------------------------------------------------- Instance Variables    
	/* The default character encoding to set for requests that pass through     
	 * this filter.     
	 */    
	protected String encoding = null;    
	
	/* The filter configuration object we are associated with.  If this value     
	 * is null, this filter instance is not currently configured.     
	 */    
	protected FilterConfig filterConfig = null;  
	
	/* Should a character encoding specified by the client be ignored?    
	 */   
	protected boolean ignore = true;    
	
	// --------------------------------------------------------- Public Methods    
	/*     * Take this filter out of service.     */    
	public void destroy() {        
		this.encoding = null;        
		this.filterConfig = null;    
	}    
	
	/** Select and set (if specified) the character encoding to be used to     
	 * interpret request parameters for this request.     
	 * @param request The servlet request we are processing     
	 * @param result The servlet response we are creating    
	 * @param chain The filter chain we are processing     
	 * @exception IOException if an input/output error occurs     
	 * @exception ServletException if a servlet error occurs    
	 */    
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {        
		// Conditionally select and set the character encoding to be used        
		if (ignore || (request.getCharacterEncoding() == null)) {            
			String encoding = selectEncoding(request);            
			if (encoding != null)                
				request.setCharacterEncoding(encoding);       
		}   // Pass control on to the next filter        
		chain.doFilter(request, response);    
	}    
	
	/** Place this filter into service.     
	 * @param filterConfig The filter configuration object     
	 */   
	public void init(FilterConfig filterConfig) throws ServletException {   
		this.filterConfig = filterConfig;        
		this.encoding = filterConfig.getInitParameter("encoding");       
		String value = filterConfig.getInitParameter("ignore");        
		if (value == null)            
			this.ignore = true;        
		else if (value.equalsIgnoreCase("true"))            
			this.ignore = true;        
		else if (value.equalsIgnoreCase("yes"))            
			this.ignore = true;        
		else            
			this.ignore = false;    
		}    
	// ------------------------------------------------------ Protected Methods    
	/**Select an appropriate character encoding to be used, based on the     
	 * characteristics of the current request and/or filter initialization     
	 * parameters.  If no character encoding should be set, return     
	 * <code>null</code>.     
	 * <p>     
	 * The default implementation unconditionally returns the value configured     
	 * by the <strong>encoding</strong> initialization parameter for this     
	 * filter.     
	 *     
	 * @param request The servlet request we are processing     
	 */   

	 protected String selectEncoding(ServletRequest request) {        
		 return (this.encoding);    
	 }
}  

